On Wed, Dec 26, 2018 at 01:27:25PM +0100, Ard Biesheuvel wrote: > If there are legal uses for vmalloc_to_page() even if the region is > not mapped down to pages [which appears to be the case here], I'd > prefer to fix vmalloc_to_page() instead of adding this hack. Or > perhaps we need a sg_xxx helper that translates any virtual address > (vmalloc or otherwise) into a scatterlist entry? What rpmsg does is completely bogus and needs to be fixed ASAP. The virtual address returned from dma_alloc_coherent must not be passed to virt_to_page or vmalloc_to_page, but only use as a kernel virtual address. It might not be backed by pages, or might create aliases that must not be used with VIVT caches. rpmsg needs to either stop trying to extract pages from dma_alloc_coherent, or just replace its use of dma_alloc_coherent with the normal page allocator and the streaming DMA API.
